Brauhenefloroside E and F; acylated flavonol glycosides from Stocksia brauhica Linn

Two new acylated flavonol glycosides, 3‐O‐{[2‐O‐β‐D ‐glucopyranosyl]‐3‐[O‐β‐D ‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]}‐α‐L ‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L ‐rhamnopyranoside and 3‐O‐{2‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]‐3‐[O‐β‐D ‐glucopyranosyl]‐4‐[(6‐O‐p‐coumaroyl)‐O‐β‐D ‐glucopyranosyl]}‐α‐L ‐rhamnopyranosyl‐kaempferol 7‐O‐α‐L ‐rhamnopyranoside, trivially named as brauhenefloroside E (1) and F (2), respectively, were isolated from the fruits of Stocksia brauhica and their structures were elucidated using spectroscopic methods, including 2D NMR experiments. Copyright © 2010 John Wiley & Sons, Ltd.     

On physical analysis of entropy measures for sodium oxide via statistical models

This study delves into a comprehensive physical analysis of entropy measures applied to sodium oxide ${\text{Na}}_2\text{O}$. A key idea in information theory and thermodynamics, entropy is essential to comprehending the stability of a system. The study clarifies the intricate relationships and physical properties of ${\text{Na}}_2\text{O}$ by combining theoretical analysis with statistical methods, providing important knowledge for material design and industrial operations. In a chemical graph, atoms are shown by vertices while their bonding are illustrated by edges. Sodium oxide is a major contributor to manufacture glass, it also has potential applications in ${\text{CO}}_2$ sequestration, transparent materials, biomedical devices and nano grating glass. A topological index is a relationship between the molecular graph and its topology. We have computed various graph entropies based on different topological indices of chemical graph of sodium oxide. Further we have integrated these graph entropies with distinct thermodynamical measures of sodium oxide by developing mathematical models between both quantities. We have developed these mathematical frameworks in MATLAB. All the models are selected relying on the least mean squared error or sum of squared error.     

Bioassay studies of cobalt (II) complexes of modified diamine

Coordination compounds of modified diamine, the basic unit of which are ethylenediamine, with that of Co (II) are prepared. The modified diamines are ethylenediaceticacid (EDDA) and N,N,N,N-tetaraethylene-1,2-diamine (TEEDA). These diamines are characterized through ¹H-NMR, ¹³C-NMR, elemental analysis and IR techniques. Cobalt (II) complexes of these two ligands were prepared and characterized by physical measurements including elemental analysis, IR, UV-Visible, magnetic susceptibilities and conductance measurements. Antibacterial activities are also carried out in order to investigate the biological activity upon complexation. They were screened against four pathogenic bacteria like Escherichia coli, Pseudomonas aeroginosa, Klesbella pneumonia and Staphylococcus aureus. The results showed significant enhancement in activities.     

A value-adding approach to reliability under preventive maintenance costs and its applications

No equipment (system) can be perfectly reliable in spite of the utmost care and best efforts on the part of the designer, decision-maker and manufacturer. The two sides of maintenance are corrective and preventive maintenance. It is generally assumed that a preventive maintenance action is less costly than a repair maintenance action. We examine this proposition in detail on the basis of a failure-time model that relates conformance quality to reliability. Illustratively, we present reliability in the context of contracts with asymmetric information. The model shows how to overcome information rents through price distortions and quantity rationing. The paper ends with a conclusion and an outlook to future studies.     

Ionization and Photofragmentation of Isolated Metalloporphyrin Cations Investigated by VUV Action Spectroscopy**

We investigated the photoionization and fragmentation of isolated metal protoporphyrin IX cations (MPPIX⁺ with M=Fe, Co, Zn) by means of vacuum-ultraviolet (VUV) action spectroscopy in the energy range of 8.5–35 eV. Experiments were carried out in the gas phase by interfacing an electrospray ionization tandem mass spectrometer with a synchrotron beamline. The mass spectra and partial ion yields show that photoexcitation of the precursor ions predominantly leads to ^.CH₂COOH radical side-chain losses of the macrocycle with additional methyl radical (^.CH₃) side-chain losses. Ionization, in contrast, leads to the formation of the intact ionized precursor and various doubly charged fragments which are mostly due to side-chain cleavages. Although statistical fragmentation dominates, we found evidence for non-statistical processes such as new fragments involving for example single and double H₂O losses, indicating that different relaxation mechanisms are at play upon photoionization compared to photoexcitation. The measured ionization energies were 9.6±0.2 eV, 9.4±0.2 eV and 9.6±0.2 eV for FePPIX⁺, CoPPIX⁺ and ZnPPIX⁺, respectively.     

Heterocyclic Compounds as Dipeptidyl Peptidase-IV Inhibitors with Special Emphasis on Oxadiazoles as Potent Anti-Diabetic Agents

Dipeptidyl peptidase-IV (DPP-IV) inhibitors, often known as gliptins, have been used to treat type 2 diabetes mellitus (T2DM). They may be combined with other medications as an additional treatment or used alone as a monotherapy. In addition to insulin, sulfonylureas, thiazolidinediones, and metformin, these molecules appear as possible therapeutic options. Oxadiazole rings have been employed in numerous different ways during drug development efforts. It has been shown that including them in the pharmacophore increases the amount of ligand that may be bound. The exceptional hydrogen bond acceptor properties of oxadiazoles and the distinct hydrocarbon bonding potential of their regioisomers have been established. Beside their anti-diabetic effects, oxadiazoles display a wide range of pharmacological properties. In this study, we made the assumption that molecules containing oxadiazole rings may afford a different approach to the treatment of diabetes, not only for controlling glycemic levels but also for preventing atherosclerosis progression and other complications associated with diabetes. It was observed that oxadiazole fusion with benzothiazole, 5-(2,5,2-trifluoroethoxy) phenyl, β-homophenylalanine, 2-methyl-2-{5-(4-chlorophenyl), diamine-bridged bis-coumarinyl, 5-aryl-2-(6′-nitrobenzofuran-2′-yl), nitrobenzofuran, and/or oxindole leads to potential anti-diabetic activity.     

Isolation,Characterization and Anticancer Activity of Two Bioactive Compounds from Arisaema flavum (Forssk.) Schott

Medicinal plants play important role in the public health sector worldwide. Natural products from medicinal plants are sources of unlimited opportunities for new drug leads because of their unique chemical diversity. Researchers have focused on exploring herbal products as potential sources for the treatment of cancer, cardiac and infectious diseases. Arisaema flavum (Forssk.) is an important medicinal plant found in the northwest Himalayan regions of Pakistan. It is a poisonous plant and is used as a remedy against snake bites and scorpion stings. In this study, two bioactive compounds were isolated from Arisaema flavum (Forssk.) and their anticancer activity was evaluated against human breast cancer cell line MCF-7 using an MTT assay. The crude extract of Arisaema flavum (Forssk.) was subjected to fractionation using different organic solvents in increasing order of polarity. The fraction indicating maximum activity was then taken for isolation of bioactive compounds using various chromatographic and spectroscopic techniques such as column chromatography, thin-layer chromatography (TLC), gas chromatography–mass spectrometry (GC-MS), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Crude extract of Arisaema flavum (Forssk.), as well as various fractions extracted in different solvents such as n-hexane, chloroform and ethyl acetate, were tested against human breast cancer cell line MCF-7 using an MTT assay. The crude extract exhibited significant dose-dependent anticancer activity with a maximum activity of 78.6% at 500 µg/mL concentration. Two compounds, hexadecanoic acid ethyl ester with molecular formula C₁₈H₃₆O₇ and molar mass 284 and 5-Oxo-19 propyl-docosanoic acid methyl ester with molecular formula C₂₆H₅₀O₃ and molecular mass 410, were isolated from chloroform fraction. These compounds were tested against the MCF-7cell line for cytotoxic activity and exhibited a significant (p < 0.00l) decrease in cell numbers for MCF-7 cells with IC₅₀ of 25 µM after 48 h of treatment. Results indicated that Arisaema flavum (Forssk.) possesses compounds with cytotoxic activity that can further be exploited to develop anticancer formulations.     

Thermogravimetric,differential scanning calorimetric,and experimental thermal transport study of functionalized nanokaolinite-doped elastomeric nanocomposites

A simple technique to synthesize and functionalize kaolinite nanoparticles having analogous shape and size in single step using layered silicate microclay as starting material is presented. The morphology, composition, and functionalization study of the activated nanokaolinite were determined by scanning electron microscopy/energy-dispersive spectroscopy, atomic-force microscope, and Fourier transform infrared spectroscopy, correspondingly. Various concentrations of activated nanokaolinite were doped in acrylonitrile butadiene rubber (NBR) by conventional industrial elastomeric mixing techniques to fabricate composite specimens. The accumulated data simulated that the thermal conductivity was diminished 92 % by increasing 15 mass% filler loading in the polymer matrix. Thermogravimetric analyzer showed that thermal stability and heat-absorbing capability were remarkably augmented by increasing activated nanokaolinite concentration in the NBR base formulation. Differential scanning calorimetric study revealed that glass transition and crystallization temperatures were reduced, whereas first and second melting phase temperatures were enhanced by increasing filler-to-host matrix ratio. Tensile strength, elongation at break, and elastic modulus at 200 % elongation were remarkably improved to a level of 144, 66, and 90 %, respectively, with increasing filler-to-matrix ratio. Efficient enhancement in elastomeric hardness was also observed.     

A profound density functional theory study to unravel the spectroscopic and molecular properties of two Flavanols differing in α-pyrone ring position

A comprehensive theoretical model was designed for two new flavanols that have been reported from Glycosmis pentaphylla, differing in the placement of α-pyrone ring. The density functional theory (DFT) approach was utilized for computing different properties of these compounds to validate the experimental findings and stereochemical assignments. Electronic properties, geometric parameters, frontier molecular orbitals (FMOs), molecular electrostatic potential (MESP), and natural bond orbital analysis were performed for the first time at the PBE0-D3BJ/def2-TZVP level of theory for the compounds under study. The simulated vibrational frequencies for compounds 1 and 2 were computed and compared with the experimental results. nuclear magnetic resonance (NMR) (¹H and ¹³C) chemical shift values were computed at the PBE0-D3BJ/def2-TZVP/SMD_DMSO level of theory and showed a very good agreement with the experimental results for both the compounds. The electronic circular dichroism (ECD) and ultraviolet–visible (UV) spectra for both the compounds were obtained using time-dependent DFT in methanol, whose results exhibited excellent correlation with experimental data. The intermolecular interaction effect on geometric parameters, vibrational frequencies, and electronic properties were studied for the first time.     

Ion‐Induced Fragmentation of Amino Acids: Effect of the Environment

In general, radiation‐induced fragmentation of small amino acids is governed by the cleavage of the C? C_α bond. We present results obtained with 300 keV Xe²⁰⁺ ions that allow molecules (glycine and valine) to be ionised at large distances without appreciable energy transfer. Also in the present case, the C? C_α bond turns out to be the weakest link and hence its scission is the dominant fragmentation channel. Intact ionised molecules are observed with very low intensities. When the molecules are embedded in a cluster of amino acids, a protective effect of the environment is observed. The fragmentation pattern changes: the C? C_α bond becomes more protected and stable amino acid cations are observed as fragments of the molecular clusters. Evidently, the molecular cluster acts as a “buffer” for the excess energy, capable of rapidly redistributing excess energy and charge.